package com.app.alldemo.utils;

import android.annotation.SuppressLint;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

@SuppressLint("TrulyRandom")
public class SecureTool {

	private final String TAG = "SecureTool";
	
	private static SecureTool tool;
	
	public static SecureTool getInstance(){
		if (tool == null) {
			tool = new SecureTool();
		}
		return tool;
	}
	
	/**
	 * 异或加密解密
	 * 
	 * @param key 加密解密的key
	 * 
	 * @param data 待加密解密的数据字符串
	 * 
	 * */
	public static String decrypt2(String key, String data) {
		String decryptString = null;
		int length = key.length();
		int start = 0;
		int keyInt;
		char[] charArray = data.toCharArray();
		for(int i = 0; i < charArray.length; i++){
			keyInt = Integer.valueOf(key.subSequence(start, start + 1).toString());
			charArray[i] = (char) (charArray[i] ^ keyInt);
			start++;
			if (start == (length - 1)){
				start = 0;
			}
		}
		decryptString =new String(charArray);
		return decryptString;
	}
	
	public static String encrypt(String seed, String cleartext){      
       try {
    	   byte[] rawKey = getRawKey(seed.getBytes());      
           byte[] result = encrypt(rawKey, cleartext.getBytes());      
           return toHex(result);   
	} catch (Exception e) {
		// TODO: handle exception
		e.printStackTrace();
		return null;
	}   
    }      
          
    public static String decrypt(String seed, String encrypted){      
        try {
        	byte[] rawKey = getRawKey(seed.getBytes());      
            byte[] enc = toByte(encrypted);      
            byte[] result = decrypt(rawKey, enc);      
            return new String(result);
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
			return null;
		}      
    }      
     
    @SuppressLint("TrulyRandom")
	private static byte[] getRawKey(byte[] seed) throws Exception {      
        KeyGenerator kgen = KeyGenerator.getInstance("AES");      
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");      
        sr.setSeed(seed);      
        kgen.init(128, sr); // 192 and 256 bits may not be available      
        SecretKey skey = kgen.generateKey();  
        byte[] raw = skey.getEncoded();      
        return raw;      
    }      
     
          
    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {      
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");      
        Cipher cipher = Cipher.getInstance("AES");      
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);      
        byte[] encrypted = cipher.doFinal(clear);      
        return encrypted;      
    }      
     
    private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {      
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");      
        Cipher cipher = Cipher.getInstance("AES");      
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);      
        byte[] decrypted = cipher.doFinal(encrypted);      
        return decrypted;      
    }      
          
    private static byte[] toByte(String hexString) {      
        int len = hexString.length()/2;      
        byte[] result = new byte[len];      
        for (int i = 0; i < len; i++)      
            result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();      
        return result;      
    }      
     
    private static String toHex(byte[] buf) {      
        if (buf == null)      
            return "";      
        StringBuffer result = new StringBuffer(2*buf.length);      
        for (int i = 0; i < buf.length; i++) {      
            appendHex(result, buf[i]);      
        }      
        return result.toString();      
    }      
    private final static String HEX = "0123456789ABCDEF";  
    
    private static void appendHex(StringBuffer sb, byte b) {      
        sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));      
    }  
}
